In Rick Elice's action-adventure play, now at Broadway's Brooks Atkinson Theatre, we learn the origin story of Peter Pan, Captain Hook, and all the other characters from the familiar classic. As they're performing, the actors create the entire world, using ropes and sheets to suggest ships and islands and turning their own bodies into hallways and doors. The jumping, posing, and tumbling give the play a uniquely physical magic.

And Celia Keenan-Bolger is jumping with everyone else. She plays Molly, a clever girl who works with her father to keep magical "star stuff" from falling into wicked hands. In the midst of a mission, she meets a group of orphaned boys who have been captured by a cruel ship's captain, and naturally, being brave, she rescues them. One of the boys is Peter (Adam Chanler-Berat), and as they become friends, they help each other through swordfights, ocean rescues, and the scary moment when you fall in love.

A character like Molly is all too rare. As Keenan-Bolger says, "In the Peter Pan story---in the J.M. Barrie story that we know and in the musical that I grew up with---Wendy is a bit of a passive observer. In telling this story, Molly is actually hugely influential. It's such a gift for me, and it's also a gift for young women and girls who get to see a strong heroine."

Keenan-Bolger has been developing her performance since 2009, when an earlier version of the play premiered at California's La Jolla Playhouse before moving to New York Theatre Workshop last year. Along the way, the show has gotten more physically demanding. For instance, Alex Timbers, who co-directs with Roger Rees, saw the cast doing a "high knees run" during a warm-up and then added it to the production.

But for all that, the actress doesn't struggle to play her character.

"It's actually less challenging than other things I've done, because it feels so tailored for me," she says. "Because I've been doing it for so long, Rick Elice and I have a real relationship---as writer and actor, but also as friends. He's been so amazing about observing me in real life, and we've done so many versions of the show that he's seen what works on me and what doesn't."

In one scene, Molly communicates with her father in Norwegian---or a comic approximation of Norwegian---and when Elice saw that Keenan-Bolger could make the bit funny, he made it longer.Keenan-Bolger argues that the show wouldn't have these personal touches, or the unique energy that comes with them, if the play hadn't started in California. "I think something happens out of town, both as a company and with the writers, because you have no life out of town," she says. "You hang out a lot. You build this bond that is just very different from what you build if you start rehearsing a Broadway show in New York City, where everybody goes home to their own life at the end of rehearsal."

Multiple productions have also given Keenan-Bolger time to reexamine her work. "Something I've been thinking about a lot is that, at that age, what you're feeling inside and how it is expressed externally are generally very different," she says. "[In earlier productions of the show], if I was feeling scared, I would just show that I was feeling scared. To my mind, I was thinking, 'Well, if you're a kid, you don't have control over that.'

"But now I remember, at this age, that it was confusing. You want to be perceived in a certain way, and you're just starting to figure out what it means to be an older person."

She says she needed multiple productions---with time off in between---to reach that level of understanding: "When you have that long to spend with a character, the time you're not working on it is almost as important and influential as the time you are working on it. You get a little perspective."